Terminal devices are located at remote sites and exchange data with a central computer system. Common examples of such devices include Point-of-Sale (POS) terminals, electronic fund transfer (EFT) devices, electronic banking machines and digital communications equipment (DCEs).
Terminal devices are generally powered by electricity provided at the remote site generated by a power adapter. If power is interrupted while the device is performing a critical task, such as modifying data or transferring data to other equipment, the validity and reliability of the task is compromised.
As such, terminal devices typically have built-in backup power circuits providing temporary reserve power to the essential circuits in the device when main power is lost. The temporary power enables the devices to complete at least the critical processes before all power is lost. Conventional methods for supplying temporary power use circuits having large voltage supplies and capacitance devices located at the power input side of the terminal device. These circuits require expensive voltage supplies and capacitors.